COMMISSION C : Radio Signals and Systems (November 2004 – October 2007)

Edited by Shozo Komaki


C1. Land Mobile Communication System


Land mobile communication systems, such as LTE and 4G communication systems, have been actively investigated in Japan for these three years. A lot of papers for OFDM-MIMO have been published in Japan. In addition, there exit a lot of technical keywords for land mobile communication systems, e.g., frequency domain equalization, Turbo equalization, multi-hop technique, cognitive radio and software defined radio (SDR).


Experimental results of MIMO transmission systems have been reported several authors.

Regarding to MIMO-OFDM, experimental results on real-time packet transmission over 1Gbps has been reported using 4 by 4 MIMO and MLD based signal detection for 4G communication systems [Higuchi et al, 2006].

Performance of 4 by 4 MIMO spatial multiplexing has been evaluated in actual indoor environment. Cumulative distribution function (CDF) of channel capacity has shown that MIMO spatial multiplexing in the LOS environment provides higher channel capacity than that in the NLOS environments [Nishimoto et al, 2007].

Regarding to MIMO eigenmode transmission system, an adaptive algorithm that accounts for channel state information (CSI) imperfection and practical operating conditions has been proposed. Experimental results and computer simulation have confirmed that this scheme is robust and superior to the conventional schemes [Ting at al, 2006].


Radio signal processing technologies for land mobile radio communication systems have been actively investigated.

Frequency domain equalization (FDE) techniques for block CDMA transmission have been investigated. It has been confirmed that frequency-domain block spread CDMA is a good solution for mitigation of performance degradation due to multi-access interference (MAI) [Adachi et al, 2007].

Frequency domain soft-interference canceling MMSE Turbo equalization has been investigated. In this paper, a computationally efficient method for computing extrinsic information transfer (EXIT) function of the equalizer has been proposed [Kansanen et al, 2007].


From the system point of view, several techniques have been proposed for performance enhancement and complexity reduction.

For OFDM/TDMA systems, channel estimation scheme has been proposed using carrier interferometry (CI). It has been confirmed that the proposed scheme can perform accurate channel estimation [Yokomakura et al, 2007].

In order to mitigate peak to average power ratio (PAPR) for single carrier PSK signals, the trellis shaping technique has been combined with iterative decoding of concatenated channel coding. Simulation results have confirmed that this scheme can achieve significant coding gain [Tanahashi et al, 2007].

In order to mitigate PAPR for MIMO-OFDM signals, subcarrier-block phase hopping scheme has been investigated. Computer simulation has confirmed that this scheme can drastically reduce PAPR and can improve its performance in comparison with the conventional MIMO-OFDM [Ishida et al, 2007].


Multi-hop cooperative sending and transmit power control based on interference information has been investigated for cognitive radio. Computer simulation results have been confirmed that this scheme is helpful to protect interference [Yu, 2007].

In order to derive accurate soft decision for reduced complexity MLD for MIMO spatial multiplexing, simple estimation method for lost likelihood information has been proposed. Computer simulation results have confirmed that this scheme has excellent performance keeping small hardware complexity [Higashinaka et al, 2007].

(H. Kubo)




Higuchi, K., H. Kawai, N. Maeda, H. Taoka, and M. Sawahashi [2006], Experiments on Real-Time 1-Gb/s Packet Transmission Using MLD-Based Signal Detection in MIMO-OFDM Broadband Radio Access, IEEE J. Sel. Areas in Commun., Volume 24, No. 6, pp. 1141-1153.


Nishimoto, H., Y. Ogawa, T. Nishimura, and T. Ohgane [2007], Measurement-Based Performance Evaluation of MIMO Spatial Multiplexing in a Multipath-Rich Indoor Environment, IEEE Trans. Antennas Propag., Vol. 55, No. 12, pp. 3677-3689.


Ting, S. H., K. Sakaguchi, and K. Araki [July 2006], A robust and low complexity adaptive algorithm for MIMO eigenmode transmission system with experimental validation, IEEE Trans. on Wireless Commun., Vol. 5, 7, pp. 1775-1784.


Adachi, F., A. Nakajima, K. Takeda, L. Liu, H. Tomeba, and K. Fukuda [2007], Frequency-Domain Equalization for Block CDMA Transmission, in Proc. of Multi-Carrier Spread Spectrum (MC-SS 2007), pp. 1-10, Herrsching, Germany, 2007.


Kansanen, K., and T. Matsumoto [2007], An Analytical Method for MMSE MIMO Turbo Equalizer EXIT Chart Computation, IEEE Trans. Wireless Commun., vol. 6, No 1, pp. 59-63.


Yokomakura, K., S. Sampei, H. Harada, and N. Morinaga [2007], A Carrier Interferometry Based Channel Estimation Technique for MIMO-OFDM/TDMA Systems, IEICE Trans. Commun., vol. E90-B, No. 5, pp. 1181-1192.


Tanahashi, M., and H. Ochiai, Iterative Decoding of Concatenated Channel Coding and Trellis Shaping Based on Markov Model, in Proc. of IEEE GLOBECOM2007, Washington D.C..


Ishida, Y., S. Suyama, H. Suzuki, and K. Fukawa [2007], MIMO-OFDM Transmission Employing Subcarrier-Block Phase Hopping for PAPR Reduction, in Proc. of VTC Spring 2007, pp. 2470-2474.


Yu, Y., H. Murata, K. Yamamoto, and K. Yoshida [2007], Multi-Hop Cooperative Sensing and Transmit Power Control based on Interference Information for Cognitive Radio, in Proc. of PIMRC 2007, pp. 1-5.


Higashinaka, M., K. Motoyoshi, T. Nagayasu, H. Kubo, A. Shibuya, and A. Okazaki [2007], Likelihood Estimation for Reduced-Complexity ML Detectors in a MIMO System, in Proc. of IEEE VTC2007-Spring, pp. 2104-2108.



C2. Satellite Communication Systems


Research and development projects in the field of satellite communication systems, such as the laser communication, mobile satellite communication, and wideband internetworking satellite communication has been executed in Japan for these three years.


(1) OICETS [T. Jono, et al., 2007]

The Optical Inter-Orbit Communication Engineering Test Satellite (OICETS, Japan name gKIRARIh) was developed by the Japan Aerospace Exploration Agency (JAXA) [K. Nakagawa, et al., 1995], [T. Jono, et al., 1999] and was launched into low earth sun-synchronous orbit at an altitude of 610 km and an inclination of 97.8 degree on 23 August 2005.


A main objective of OICETS was to demonstrate the free-space inter-orbit laser communications (forward: 2.048Mbps, return: 49.3724Mbps) by using of intensity modulation, or On-Off Keying (OOK) and direct detection system. 


The inter-orbit demonstration was carried out with the cooperation of the Geostationary Earth Orbit (GEO) satellite, the Advanced Relay and Technology Mission (ARTEMIS) developed by the European Space Agency (ESA) [M. Faup, et al., 1996], [T. T. Nielsen, et al., 2002].  These results show more than 90 % probability of acquisition and less than 10-6 bit error rate.  Moreover, a Low Earth Orbit (LEO) to ground laser bi-directional communication demonstration was carried out with the cooperation of the Optical Ground Stations (OGSs), one of which was developed by the National Institute of Information and Communications Technology (NICT) in Japan, and the acquisition and tracking of the OICETS satellite were successful by 100 % without bad weather conditions and the bidirectional optical communication link was successfully established [M. Toyoshima, et al., 2006].  The other portable OGS was developed by the German Aerospace Center (DLR) and the optical downlink experiment was conducted on European grounds [N. Perlot, et al., 2007].



The Engineering Test Satellite VIII (ETS-VIII, Japanese name gKIKU-8h) was developed by the JAXA, NICT, and Nippon Telegraph and Telephone Corporation (NTT) and was launched into geostationary orbit at 146 degrees east longitude on 18 Dec. 2006.


The aim of this project is to develop fundamental technologies for mobile satellite handheld phone services and digital sound broadcasting services using the S-band frequency [N. Hamamoto, et al., 2003].  The goal of this project are to develop the following new technologies, in-orbit tests, and experiments such as large-scale satellite-borne deployable reflector (19m x 17m), mobile satellite communications using small ground stations such as handheld terminals ( about 300g ) [K. Yonezawa, et al., 1998], [Y. Kawakami, et al., 1998]. 


This satellite was shifted to operational phase in May 2007 after 4-months in-orbit tests.  The demonstrations of data/video transmission and the voice communication via this satellite that assumed the use in the disaster spot were carried out in Sep. 2007 and Jan. 2008.  The basic experiments and the application experiments will be performed for several years.



Wideband Internetworking engineering test and Demonstration Satellite (WINDS) is an experimental satellite aiming at research and development of broadband satellite communications system which takes part in construction of worldwide broadband networks. 


Its origin is the Gigabit Satellite R&D started in Communications Research Laboratory (CRL, one of former bodies of NICT ) in 1992, and fundamental technologies such as Ka-band active phased array antenna, satellite onboard modem and high speed baseband switch were developed in this project [N. Kadowaki, et al., 1999]. From 2001, full scale experimental satellite project as WINDS executes by JAXA and NICT [N. Kadowaki, et al., 2007].


This satellite is equipped with the Multi-Beam Antenna (MBA), the Multi-Port Amplifier (MBA), the Ka-Band Active Phased Array Antenna (APAA), and the Advanced Baseband Switch (ABS) as the key sub-systems.  The data transmission is up to 2 channels of 1.2 Gbps using 5 m class aperture antenna in bent-pipe mode and 3 channels of 155 Mbps using 45 cm aperture antennas in on-board switching mode.  This satellite was launched into geostationary orbit in Feb. 2008.

(A. Kato)




 T. Jono, Y. Takayama, K. Shiratama, I. Mase, B. Demelenne, Z. Sodnik, A. Bird, M. Toyoshima, H. Kunimori, D. Giggenbach, N. Perlot, M. Knapek and K. Arai [2007] gOverview of the inter-orbit and orbit-to-ground laser communication demonstration by OICETSh, Proc. of SPIE Vol. 6457, 645702.


 K. Nakagawa, et al. [1995] gPreliminary design of Laser Utilizing Communications Experiment (LUCE) installed on Optical Inter-Orbit Communications Engineering Test Satellite (OICETS),h Proceedings of the SPIE 2381, 14-25.


T. Jono, et al. [1999] gAcquisition, tracking and pointing system of OICETS for free space laser communications,h Proceedings of the SPIE 3692, 41-50.


M. Faup, et al. [1996] gExperience Gained in the Frame of Silex Program Development and Future Trends,h AIAA 16th International Communications Satellite Systems Conference 1996, 782-783.


T. T. Nielsen, et al. [2002] gIn Orbit test result of an Operational Intersatellite Link between ARTEMIS and SPOT4,h Proceedings of the SPIE Vol. 4635, 1-15.


M. Toyoshima, K. Takizawa, T. Kuri, W. Klaus, M. Toyoda, H. Kunimori, T. Jono, Y. Takayama, N. Kura, K. Ohinata, K. Arai, K. Shiratama [2006], "Ground-to-OICETS laser communication experiments," Proceedings of the SPIE, vol.6304-75, pp. 1-8, San Diego, U.S.A., August 13-17.


N. Perlot; M. Knapek; D. Giggenbach; J. Horwath; M. Brechtelsbauer; Y. Takayama; T. Jono [2007], gResults of the optical downlink experiment KIODO from OICETS satellite to optical ground station Oberpfaffenhofen (OGS-OP),h Proceedings of the SPIE, Vol. 6457.


N. Hamamoto, S. Yoshimoto, M. Imae [2003]  gOverview of the Engineering Test Satellite VIII (ETS-VIII) Project,h Journal of the National Institute of Information and Communications Technology, Vol. 50, No. 3/4.


K. Yonezawa, M. Homma, S. Yoshimoto, S. Hama, T. Ohira, N. Natori, Y. Tsutsumi [1998] gOutline of Engineering Test Satellite VIII,h 21st  International Symposium on Space and Tech. and Sci., ISTS 98-h-01V, Omiya, Japan.


Y. Kawakami, S. Yoshimoto, Y. Matsumoto, T. Ohira, N. Hamamoto [1998] gS-band Mobile Satellite Communications and Sound Broadcasting System in ETS-VIII,h 21st  International Syposium on Space and Tech. and Sci., ISTS 98-h-02, Omiya, Japan.


N. Kadowaki, R. Suzuki [2007] gOverview of the Wideband InterNetworking Engineering Test and Demonstration Satellite Project,h Journal of the National Institute of Information and Communications Technology, Vol. 54, No. 4.


N. Kadowaki, N. Yoshimura, Y. Ogawa, N. Komiya, T. Araki [1999] gKa-Band Gigabit Communications Satellite: Development Status and Connection Control Scheme,h Proceedings of 5th Ka-Band Utilization Conference, Taormina, Italy.



C3. Digital Broadcasting System


There are many research and development activities in the field of digital broadcasting system such as digital terrestrial television broadcasting (DTTB) and television broadcasting for mobile in Japan for these three years.


Japanese digital television standard, ISDB-T (Integrated Services Digital Broadcasting for Terrestrial), has already been standardized by the Japanese radio and broadcasting standardization body, ARIB (Association of Radio Industries and Businesses) in 2001[ARIB, 2001]. DTTB service based on ISDB-T began in 2003 at Tokyo, Nagoya and Osaka, and deployed all the major cities in Japan at the end of 2006. ISDB-T employs OFDM (Orthogonal Frequency Division Multiplex) technique as well as the European DTTB standard, DVB-T (Digital Video Broadcasting for terrestrial). The ISDB-T signal is transmitted through 5.6MHz frequency band composed of 13 frequency segments. Each segment has a bandwidth of 432kHz. It is capable of using a part of segments for transmitting different programs and can be received by a narrowband receiver. DTTB service dedicated for mobile phones and terminals, which use one out of 13 segments for mobile, began on April 2006.


Since battery size is strictly limited in mobile and handheld terminals, power consumption of the narrow-band ISDB-T receiver is a major problem. An RF (Radio Frequency) front-end circuit, whose bias is controlled by the received signal quality, was developed in order to reduce the average power consumption [Sakai, 2007]. The proposed RF front-end has two modes. The one is low-NF and high power consumption mode, and the other is high-NF and low power consumption one. The baseband module measures the modulation error ratio (MER) at the quadrature amplitude modulation (QAM) demapper, and controls RF front-end. The low NF mode is chosen when MER is lower than the threshold. In order to further minimize the power consumption, an improved control algorithm was proposed [Kim,, 2007]. This scheme uses MER as a control criterion. However, the low NF mode is used only in the region around the target MER.


The multipath fading and Doppler spreading are major problems especially in the reception of DTTB on fast moving vehicle. In order to solve these problems, joint use of the pre-FFT (Fast Fourier Transform) combining adaptive array antenna and post-FFT space diversity combining was proposed [Pham, 2006, 2008]. The Doppler spread compensator based on linear array antenna was proposed [Yu, 2007].


Although ISDB-T is robust to multipath and the required CNR (Carrier-to-Noise power Ratio) is lower than that of analog television, poor reception areas still remain in shadowed areas. In order to reduce the poor reception areas, retransmission is made based on the radio-on-fiber (RoF) technique [Maeda,, 2005].

(M. Okada)




ARIB STANDARD STD-B31, Transmission system for digital terrestrial television broadcasting, [2005]

(first version was released in 2001 and the version 1.6 was revised in 2005 as version 1.6)


Digital broadcasting experts group (DiBEG) Web Page,


Sakai, T., Ito, S., Kaiki, N., Sakai, A., Okazaki, M., Natsumi, M., Saito, A., Kioi, K., Koutani, M., Kagoshima, K., Kawama, S., Kijima, H., Toyoyama, S., Matsunaga, N., Hamaguchi, M., Kawamura, H., Iizuka, K. [2007], A Digital TV Receiver RF and BB Chipset with Adaptive Bias-Current Control for Mobile Applications, IEEE International Solid-State Circuits Conference, 2007. ISSCC 2007. Digest of Technical Papers, pp. 212-213.


Kim, S-H., Okada, M. Hara, T., Saito, M., [2007], A study on the adaptive RF Front-end for low power consumption ISDB-T Receiver, Military Communications Conference.


Pham, D-H., Tabata, T., Asato, H., Hori, S., Wada, T.,[2006], Joint Hardware-Software Implementation of Adaptive Array Antenna for ISDB-T Reception, Vol.E89-B, No.12, pp.3215-3224


Pham, D.-H., Gao, J., Tabata T., Asato, H., Hori, S. Wada, T. [2008], Implementation of Joint Pre-FFT Adaptive Array Antenna and Post-FFT Space Diversity Combining for Mobile ISDB-T Receiver,, IEICE Transactions on Communications. Vol.E91-B, No.1, pp.127-138


Yu, Y-C., Okada, M., Yamamoto, H. [2007], Dipole Array Antenna Assisted Doppler Spread Compensator with MRC Diversity for ISDB-T Receiver, IEICE Transactions on Communications, Vol.E90-B, No.5, pp.1214-1221


Maeda, M., Nakatsugawa, T., Oyamada, K. [2005], Optical Fiber Transmission Technologies for Digital Terrestrial Broadcasting Signals, IEICE Transactions on Communications, Vol.E88-B, No.5, pp.1853-1860



C4. Array Antenna and Signal Processing


Research and development activity in the field of radio communication systems, such as the fourth-generation mobile/cellular radio and wireless LAN systems has been very active in Japan for these three years.  Especially, MIMO propagation [Y. Karasawa, 2005], [Y. Ogawa, et al., 2005] and capacity analysis in case of multi-keyhole environment [M. Tsuruta, et al., 2007] were conducted.


Development of Experimental setup and experimental study on MIMO system were also well investigated. Platforms for MIMO systems were developed [K. Mizutani, et al., 2006], and transmission performance was measured [H. Nishimoto, et al., 2007]. Devices for MIMO system such as dual polarization antenna [N. Kumar, et al., 2006] and beam-scanning array antenna with tunable reactance devices were also developed [N. Honma, et al., [2005].


Study on adaptive arrays and SDMA (Space Division Multiple Access) technologies have still active in this period.  Performance of several SDMA techniques were compared [Y.Jia, et al., 2006] and SDMA configuration using polarization control was proposed [K. Komiya, et al., 2005]. Furthermore, an adaptive beamforming method using MEMS [Q. Tran, et al., [2006] and real-time ML detectors [T. Koike, et al., 2006] for SDMA were developed.


Array signal processing for terrestrial television broadcasting were very active because the digital broadcasting based on OFDM technology was serviced in the end of 2003.  A pre-FFT OFDM adaptive array with eigenvector combining was proposed [S. Hara, et al., 2006]. A Doppler spread compensator using dipole array antenna [Y. Yu, et al., 2007] and implementation of adaptive array antenna for digital television broadcasting [D. Pham, et al., 2006] was well investigated.


Estimation of direction of arrival was also one of the attractive issues in the array signal processing. Since the estimation techniques utilizing signal sub-space concept has very high resolution performance, the research in this field was very active [N. Kikuma, 2005]. Not only estimation for the direction of arrival but also the estimation for number of arrival waves were studied [Y. Ishikawa, et al., 2006]. It was also reported that the estimation accuracy was improved by calibration and spatial smoothing [P. Cherntanomwong, et al., 2007].

 (M. Fujimoto)




Y. Karasawa [2005], MIMO propagation channel modeling, IEICE Trans. Commun., Vol.E88-B, No.5, pp.1829-1842.


Y. Ogawa, K. Nishio, T. Nishimura, T. Ohgane [2005], Channel estimation and aignal detection for space division multiplexing in a MIMO-OFDM system, IEICE Trans., Commun., Vol.E88-B, No.1, pp.10-18.


M. Tsuruta, T. Taniguchi, Y. Karasawa [2007], On statistical distribution of eigenvalues of channel correlation matrix in MIMO multi-keyhole environment, IEICE Trans. Commun., Vol.E90-B, No.9, pp.2352-2359.


R. Kudo, Y. Takatori, K. Nishimori, K. Tsunekawa [2006],  Novel downlink beamforming method using selective STBC with common eigenvectors for MIMO-OFDM systems, IEICE Trans. Commun., Vol.E89-B, No.8, pp.2170-2179.


K. Mizutani, K. Sakaguchi, J. Takada, K. Araki [2006], Development of MIMO-SDR platform and its application to real-time channel measurements, IEICE Trans. Commun., Vol.E89-B, No.12, pp.3197-3207.


H. Nishimoto, Y. Ogawa, T. Nishimura, T. Ohgane [2007], MIMO E-SDM transmission performance in an actual indoor environment, IEICE Trans. Commun., Vol.E90-B, No.6, pp.1474-1486.


T. Onizawa, A. Ohta, Y. Asai, S. Aikawa [2006], FPGA implementation of eigenbeam MIMO-OFDM for wireless LAN and its experimental performance, IEICE Trans. Commun., Vol.E89-B, No.12, pp.3233-3241.


N. Kumar, M. Shinozawa, N. Miyadai, T. Taniguchi, Y. Karasawa [2006], Experiments on a MIMO system having dual polarization diversity branches, IEICE Trans. Commun., Vol.E89-B, No.9, pp.2522-2529.


N. Honma, T. Seki, K. Nishikawa, K. Tsunekawa, K. Sawaya [2005], Series-fed beam-scanning antenna employing multi-stage configured microstrip antennas with tunable reactance devices, IEICE Trans. Commun., Vol.E88-B, No.6, pp.2297-2304.


Y.Jia, Q. Tran, S. Hara [2006], Performance comparison of two SDMA approaches for OFDM signals using measured indoor channel data, IEICE Trans. Commun., Vol.E89-B, No.4, pp.1315-1324.


K. Komiya, K. Nishimori, K. Cho, T. Hori [2005], Proposal of SDMA configuration adopting directivity and polarization control, IEICE Trans. Commun., Vol. J88-B, No. 7, pp.1289-1299, (Japanese edition).


Q. Tran, S. Hara, Y. Nakaya, I. Ida, Y. Oishi [2006], An adaptive beamforming method for phased array antenna with MEMS phase shifters, IEICE Trans. Commun., Vol.E89-B, No.9, pp.2503-2513.


T. Koike, Y. Seki, H. Murata, S. Yoshida, K. Araki [2006], Prototype implementation of real-time ML detectors for spatial multiplexing transmission, IEICE Trans. Commun., Vol.E89-B, No.3, pp.845-852.


S. Hara, Q. Tran, Y. Jia, M. Budsabathon, Y. Hara [2006], A pre-FFT OFDM adaptive array antenna with eigenvector combining, IEICE Trans. Commun., Vol.E89-B, No.8, pp.2180-2188.


Y. Yu, M. Okada, H. Yamamoto [2007], Dipole array antenna assisted doppler spread compensator with MRC diversity for ISDB-T receiver, IEICE Trans. Commun., Vol.E90-B, No.5, pp.1214-1221.


D. Pham, T. Tabata, H. Asato, S. Hori, T. Wada [2006], Joint hardware-software implementation of adaptive array antenna for ISDB-T reception, IEICE Trans. Commun., Vol.E89-B, No.12, pp.3215-3224.


N. Kikuma [2005], Iterative DOA estimation using subspace tracking methods and adaptive beamforming, IEICE Trans. Commun., Vol.E88-B, No.5, pp.1818-1828.


Y. Ishikawa, K. Ichige, H. Arai [2006], Accurate source number detection using pre-estimated signal subspace, IEICE Trans. Commun., Vol.E89-B, No.12, pp.3257-3265.


P. Cherntanomwong, J. Takada, H. Tsuji [2007], Accurate angle-of-arrival estimation method in real system by applying calibration and spatial smoothing, IEICE Trans. Commun., Vol.E90-B, No.10, pp.2915-2925.



C5. Radio Resource Management


Recent research and developments in the field of radio resource managements for cellular, wireless LAN, other wireless access, and heterogeneous wireless, have been still active in these three years, and many researches for cross layer management which provide radio and network resource managements on the cross layers combined with Layer 1, 2, 3 and uppers, have been found. The lack of radio frequency resources has been more and more serious and in order to improve the spectrum utilization efficiency, system capacity, or throughput, the cooperation among physical and upper layers has become important.


For the evolved UTRA, Single-Carrier (SC)-FDMA based multiplexing of L1/L2 control signaling was proposed for downlink scheduling, link adaptation, hybrid ARQ (automatic repeat request) with soft-combining [Kawamura et. al., 2007]. The software defined radio platform for W-CDMA, IEEE802.11a/b, and digital terrestrial broadcasting have been developed toward user centric radio resource management for cognitive radio communication systems [Harada, H. 2005].

In the field of WLAN systems, which share a few channel in unlicensed band and are provided by many AP set up in disorder, many radio resource managements cooperated among multi-layers have been proposed. A fair allocation method of radio resources in WLAN area overlapped among different domains was proposed [Matsunaga et. al., 2004]. An adaptive resource allocation scheme for video stream according to video stream character and user mobility in WLAN was proposed [Minoda et. al., 2005]. Some AP selection methods based on 802.11e standard have been developed. An association mechanism called HRFA (high-rate first association) in IEEE802.11e WLAN networks was proposed to achieve the load balancing and efficient use of radio resources [Takeuchi et. al., 2007]. Radio Agent selecting a proper AP among QAPs (QoS supported AP) and non-supported APs to satisfy both of load balancing and QoS was proposed by using the presence function of SIP (session initiation protocol) in Layer 7 [Morioka et. al, 2006] A new wireless resource management mechanism with AP resource management server with SIP proxy and 802.1x authentication server was proposed to guarantee minimum available WLAN bandwidth for real-time applications [Tamura et. al., 2005]. A cooperative scheme for APs and STAs in order to attain efficient and fair sharing of resources of WLAN was proposed and its prototype system was developed [Fukuda et. al., 2007]. In order to QoS guarantee in home networks composed with wired and wireless Ethernet, a new mechanism development for topology discovery and resource reservation have been also started in the consumer communications [Ando et. al., 2004].


Researches in user centric radio resource managements have been also active. A novel mechanism was proposed for a mobile user to select an optimal network from the heterogeneous multimedia networks based on the user-centric performance, that is the user-perceived quality of service (QoS) and user-centric cost, that is measured by the user's willingness to pay the price and allow for the consumption of the mobile terminal's resources [Kafle et. al., 2005]. In order to realize user centric resource management, quality of experience (QoE) measure that is the user utility for different types of wireless services is required. The utility for the video quality and video download services were measured by subjective assessments, and a new service management scheme to maximize user utility for given throughput was proposed [Shutto et. al., 2007].

(K. Tsukamoto)




Kawamura, T.; Kishiyama, Y.; Higuchi, K.; Sawahashi M. [2007], Layer 1/layer 2 control channel structure in single-carrier FDMA based evolved UTRA uplink, 2007 IEEE 65th Vehicular Technology Conference, 2941-5, Dublin, Ireland.


Harada, H. [2005], Software defined radio prototype toward cognitive radio communication systems, 2005 1st IEEE International Symposium on New Frontiers in Dynamic Spectrum Access Networks, 539-47, Baltimore, MD, USA.


Matsunaga, Y.; Katz, R.H. [2004], Inter-domain radio resource management for wireless LANs, 2004 IEEE Wireless Communications and Networking Conference, Vol.4, 2183-8 Atlanta, GA, USA.


Minoda, Y.; Tsukamoto, K.; Komaki [2005], Adaptive resource allocation for video stream based on video stream character and user mobility in wireless LAN, IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, Vol. E88-A, n 7, July 2005, 1881-8.


Takeuchi, S.; Sezaki, K.; Yasuda, Y. [2007], Access point selection strategy in IEEE802.11e WLAN networks toward load balancing, Electronics and Communications in Japan, Part 1 (Communications), Vol. 90, No. 4, 35-45.


Y. Morioka, Y. Minoda, T. Higashino, K. Tsukamoto, S. Komaki [2006], "Proposal of AP selection Scheme for QoS Guarantee in Wireless LAN, COIN-NGNCON2006, pp.30-32.


Tamura, T.; Ito, T. [2005], Wireless LAN resource management mechanism guaranteeing minimum available bandwidth for real-time communication, 2005 IEEE Wireless Communications and Networking Conference, Vol. 3, 1596-601, New Orleans, LA, USA


Fukuda, Y.; Layawickrema, M.; Oie, Y. [2007], Cooperative resource management by access points and stations for fair and efficient sharing of wireless LANs, 2007 Next Generation Internet Networks. 3rd EuroNGI Conference on Next Generation Internet Networks Design and Engineering for Heterogeneity, 64-71, Trondheim, Norway.


Ando, S.; Ohmoto, M.; Shimizu, Y. [2004], QoS technology for home networks, 1st IEEE Consumer Communications and Networking Conference, 19-24, Las Vegas, NV, USA.


Kafle, B.P.; Kamioka, E.; Yamada S. [2005], User-centric performance and cost analysis for selecting access networks in heterogeneous overlay systems, 8th International Conference on Management of Multimedia Networks and Services, MMNS 2005, 277-88, Barcelona, Spain.


Shutto, N.; Handa, Y.; Higashino, T.; Tsukamoto, K.; Komaki, S. [2007], Measurements of a utility function for video download service and its application to service management, 2007 8th IEEE Wireless Communications and Networking Conference, Kowloon, China.



C6. Microwave Passive Circuit


With the development of Wireless communication system, high performance of small-size, low-loss, multi-band, and wideband are required for microwave and millimeter-wave passive devices such as a resonator, filter, power divider/combiner and directional coupler, etc. Several approaches and new techniques are currently in the practice for their development purposes.


Reduced-size couplers with planar circuit-type have been reported using lumped-element circuits[J. Yamasaki, et al., 2005], slow-wave structures [T. Fujii, et al., 2005, 2007], and broadband / multi-band dividers/couplers have been developed [T. Kawai, et al., 2006], [S. Tanigawa, et al., 2007]. Microstrip-type multi-way power dividers with broadband characteristics can be obtained [M. Kishihara, et al., 2006]. Moreover, miniature planar filters have been developed using High-Temperature Superconductor [Z. Ma et al., 2006], and several types of UWB filters have been reported [K. Li et al., and D. Kurita et al., 2007]


Several components such as corner [K. Toda, et al., 2006], directional couplers [M.Kishihara, et al., 2007] in E-plane and H-plane waveguide have also been illustrated based on E-plane and H-plane circuit approaches. Furthermore, Substrate-Integrated Waveguide (SIW) hybrids [I. Ohta et al., 2007] based on above design procedure are proposed, these circuit are useful for millimeter-wave regions. Waveguide filters and resonators using frequency selective surfaces have been reported [H. Ohira et al., 2005], and leakage properties of stub-loaded ridge-rectangular waveguides have been rigorously analyzed [M. Tsuji et al., 2005]


Furthermore, study and development of metamaterials include double negative or left-handed materials have been active in these years. Novel two-dimensional negative refractive index structure has been reported [N. Matsunaga et al., 2006], and its application to antenna system has been developed [T. Kaneda et al., and S. Matsunaga et al., 2006].

(T. Kawai)




J. Yamasaki, I. Ohta, T. Kawai, and Y. Kokubo [2005], Design of Broadband Semi-Lumped and Lumped Element Quadrature Hybrids, IEEE MTT-S Intfl Microwave Symposium Digest (CD ROM), WEPI-11.


T. Fujii and I. Ohta [2005], Size-Reduction of Coupled-Microstrip 3 dB Forward Couplers by Loading with Periodic Shunt Capacitive Stubs, IEEE MTT-S Intfl Microwave Symposium Digest (CD ROM)CWEPI-8.


T. Fujii, I. Ohta, T. Kawai, and Y. Kokubo [2007], Miniature Broad-Band CPW 3-dB Branch-Line Couplers in Slow-Wave Structure, IEICE Transaction on Electronics, Vol.E-90C, No.12, pp. 2245-2253.


T. Kawai, J. Yamasaki, Y. Kokubo, and I. Ohta [2006], A Design Method of Dual-Frequency Wilkinson Power Divider, 2006 Asia-Pacific Microwave Conference Proc., pp. 913-916.


S. Tanigawa, K. Hayashi, T. Fujii, T. Kawai, and I. Ohta [2007], Tri-Band/Broadband Matching Techniques for 3-dB Branch-Line Couplers, Proc. 37th European Microwave Conference (CD ROM), pp. 560-563.


M. Kishihara, I. Ohta, and K. Yamane [2006], Multi-Stage, Multi-Way Microstrip Power Dividers with Broadband Properties

IEICE Transaction on Electronics, Vol.E89-C, No.5, pp.622-629


Z. Ma, T. Kawaguchi, and Y. Kobayashi [2005], Miniaturized High-Temperature Superconductor Bandpass Filters Using Microstrip S-Type Spiral Resonators, IEICE Transaction on Electronics, Vol.E88-C, No.1, pp.57-61


Z. Ma, and Y. Kobayashi [2005], Miniaturized High-Temperature Superconducting Microstrip and Coplanar Waveguide Filters, IEICE Transaction on Electronics, Vol.E88-C, No.7, pp.1406-1411


K. Li, Y. Yamamoto, D. Kurita, and O. Hashimoto [2007], An Ultra-Wideband (UWB) Bandpass Filter Using Broadside-Coupled Structure and Lumped-Capacitor-Loaded Shunt Stub Resonators, IEICE Transaction on Electronics, Vol.E90-C, No.9, pp.1736-1742.


D. Kurita, and K. Li [2007], Notch-Band Implemented UWB Bandpass Filter, IEICE Transaction on Electronics, Vol.E90-C, No.12, pp.2226-2231.


K. Toda, I. Ohta, and M. Kishihara [2006], A Broadband, Low-Reflection H-Plane Waveguide Corner with a Dielectric Circular Post, 2006 Asia-Pacific Microwave Conference Proc., pp. 1908-1911.


M. Kishihara, I. Ohta, and K. Yamane [2007], Cruciform Directional Couplers in E-Plane Rectangular Waveguide, IEICE Transaction on Electronics, vol.E90-C, no.9, pp.1743-1748.


I. Ohta, K. Toda, M. Kishihara, and T. Kawai [2007], Design of Cruciform Substrate-Integrated Waveguide Hybrids Based on H-Plane Planar Circuit Approach, 2007 Asia-Pacific Microwave Conference Proc., pp. 683-686


M. Ohira, H. Deguchi, M. Tsuji, and H. Shigesawa [2005], Novel waveguide filters with multiple attenuation poles using dual-behavior resonance of frequency selective surfaces, IEEE Trans. Microwave Theory Tech., vol. 53, No. 11, pp. 3320-3326.


M. Ohira, H. Deguchi, M. Tsuji, and H. Shigesawa [2005], Novel dual-resonant and dual-polarized frequency selective surface using eight-legged element and its experimental verification, IEICE Trans. on Electron., vol. E88-C, No. 12, pp. 2229-2235.


M. Tsuji, and H. Shigesawa [2005], Leakage properties of stub-loaded ridge-rectangular waveguides, IEICE Trans. on Electron., vol. E88-C, No.9, pp. 1853-1859.


N. Matsunaga, A. Sanada, H. Kubo [2006], Novel Two-Dimensional Planar Negative Refractive Index Structure,  IEICE Trans. on Electron., vol. E89-C, No.9, pp. 1276-1282 .


T. Kaneda, A. Sanada, H. Kubo [2006], 2D Beam Scanning Planar Antenna Array Using Composite Right/Left-Handed Leaky Wave Antennas,  IEICE Trans. on Electron., vol. E 89-C, No.12, pp. 1904-1911.


S. Matsuzawa, K. Sato, S. Aso, A. Sanada, H. Kubo [2006], A W-Band Microstrip Composite Right/Left-Handed Leaky Wave Antenna, IEICE Trans. on Communications, E89-B, April, pp. 1464-1466.



C7. Microwave Active Circuit


In RF/Microwave/Millimeter wave region, we have two major evolutions of semiconductor device: high frequency performance of submicron CMOS device and high breakdown voltage/high frequency performance of the wide band-gap device.


Regarding the first topic of above, lithography rule for large scale logics is still shifting to deep sub-micron less than 65nm in 2007 [STARC 2007] in Japan, as in world-wide roadmap [ITRS 2007]. The cutoff frequency of CMOS transistor reaches over-100GHz. This means good capability of Millimeter wave CMOS transistor.  For high-speed radio transceivers, Millimeter wave CMOS RF-ICs have been reported for radio functionalities [Shigematsu 2005], [Mitomo 2007] [Ishibashi 2007] of low noise amplifiers, frequency mixers, oscillators and frequency dividers. In parallel, RF-system level constructions have been done for Gbps-class radio transmission systems with GaAs device [Maruhashi 2005]. Millimeter wave CMOS devices have been applied to the similar systems, instead of GaAs devices [Mitomo 2007].


Regarding the second topic, high voltage operation and high frequency one are in the trade-off issue. Thus there are two research directions toward high power and high frequency in wide band-gap devices as GaN. The C-band GaN HEMT amplifier has achieved output power of 220W in pulse operation by optimization of electrode-layout for thermal resistance reduction, [Yamanaka 2007]. The Ka-band AlGaN/GaN HEMT with quarter-micron T-shaped gate has achieved output power of 5.8 W in CW and linear gain of 9.2 dB [Inoue 2005].


In addition to above topics based on semiconductor improvements, there have been the following technical interests.


For the next generation mobile communication system as WiMAX and LTE, multi-carrier systems employed for high speed radio transmission.  This makes higher crest factor in modulated signal in transmitters and higher dc power for keeping low leakage power to adjacent channel. For improvement of non-linear distortion in HPAs, several system-level approaches have been demonstrated. In [Matsunaga 2007], DC bias voltage is controlled by envelope voltage of input modulated signal. In [Horiguchi 2007], combination of digital predistortion architecture and improved Doherty amplifier has been demonstrated for OFDM transmitters.


In future cellular phone system, we have additional frequency resources after termination of analog TV system in Japan. In the situation, multi-band frequency allocation for cellular phone system will be done to increase transmission capacity. MEMS migrated high power amplifier has been proposed for small sized/high efficiency multi-band high power amplifier [Fukuda 2005].


Phase noise of oscillators has been represented by well-known Leesonfs formula with oscillatorsf Q. However, we had no clear definition of oscillatorsf Q.  In [Ohira 2007], theoretical formulas of oscillatorsf Q can be defined under the circuit theory.  The substituted formulas are effective for low noise oscillator design.

 (K. Itoh)




STARC (The Semiconductor Technology Academic Research Center) [2007], (in Japanese)


ITRS (International Technology Roadmap for Semiconductors) [2007],


Shigematsu, H., Hirose,,T.,, [2005], Millimeter-wave CMOS circuit design,  IEEE Transactions on Microwave Theory and Techniques, Vol.53, No.2, pp. 472-477.


Mitomo, T., Fujimoto, R., Ono, N., [2007], A 60-GHz CMOS Receiver with Frequency Synthesizer, Proceedings of2007 IEEE Symposium on VLSI Circuits, pp.172-173.


Ishibashi, K., Motoyoshi, M., Kobayashi, N., Fujishima, M. [2007], 76GHz CMOS Voltage-Controlled Oscillator with 7% Frequency Tuning Range, Proceedings of 2007 IEEE Symposium on VLSI Circuits, pp.176-177.


Maruhashi, K., Ito,, M. Kishimoto,, S. Ohata, K. [2005], 60-GHz-band LTCC module technology for wireless gigabit transceiver applications, Proceedings of 2005 IEEE International Workshop on Radio-Frequency Integration Technology pp. 131- 134.


Yamanaka, K., Mori, K., Iyomasa, K., [2007], C-band GaN HEMT Power Amplifier with 220W Output Power, 2007 IEEE/MTT-S International Microwave Symposium Digest, pp.1251-1254.


Inoue, T., Ando, Y., Miyamoto, H.,,[2005], 30-GHz-band over 5-W power performance of short-channel AlGaN/GaN heterojunction FETs,  IEEE Transactions on Microwave Theory and Techniques, Vol. 53,  No.1, pp.74- 80.


Matsunaga, K., Tanomura, M., Nakayama, T.,, Analogue Dynamic Supply Voltage L-band GaN High Power Amplifier with Improvement of Efficiency and Linearity, 2007. IEEE/MTT-S International Microwave Symposium Digest, pp.1107-1110.


Horiguchi, K., Ishizaka, S., Nakayama M., [2007], Efficiency Enhancement of a Digital Predistortion Doherty Amplifier Transmitter Using a Virtual Open Stub Technique,  IEICE TRANSACTIONS on Electronics, Vol.E90-C,  No.9,  pp.1670-1677.


Fukuda, A., Okazaki, H., Narahashi, S., Hirota. T., Yamao, Y., [2005], A 900/1500/2000-MHz triple-band reconfigurable power amplifier employing RF-MEMS switches, 2005 IEEE MTT-S International Microwave Symposium Digest,  pp.657-660.


Ohira, T., Araki, K. [2007], Active Q-Factor and Equilibrium Stability Formulation for Sinusoidal Oscillators, IEEE Transactions on Circuits and Systems II, Vol. 54, No.9, pp.810-814



C8. UHF Band RFID System


RFID (Radio Frequency Identification) is an automatic recognition technology that accesses data in the memory of the integrated circuit chip by using a radio communication technology. The one that the antenna was connected with the RFID chip is called the RFID tag. RFID tag is called IC tag. Passive type RFID tag doesn't have the battery, rectifies the electromagnetic radiation from the tag reader/writer, and operates the circuit. Moreover, it doesn't have the radio frequency transmitter in oneself so that RFID tag may reply by the back scattering method. The application starts in wide fields of the production line of the factor, the personal authentication, distribution, and the circulation, etc. RFID is international standardized as ISO18000 series. 915MHz band, it is ISM band, is used in the United States etc. for UHF band RFID, and 860MHz band is used in Europe etc. 950MHz band became the candidate of UHF band RFID in Japan. PDC (Personal Digital Cellular) system had used 950MHz band in Japan, the cellular phone system had changed to CDMA (Code Division Multiple Access) system from PDC, so 950MHz band is not used by cellar phone system in 1994. 


The trial experiment of UHF band RFID came to be conducted in various industrial fields such as construction, publication, the consumer electronic, the medicines, and department stores from 1994[J. Mitsugi, et al.,2006],[ Y. Kawakita, et al.,2006]. A severe regulation was provided for a spurious radiation because the cellular phone used the frequency of neighborhood in Japan. 950MHz band became possible the legal use of RFID in April, 1995. Moreover, the interference avoidance technology between the reader writers by the career sense method was included in the law in January, 1996.


As the research and development concerning the integrated circuit chip for RFID tag, the Ministry of Economy, Trade and Industry promoted the project gHibikih that was the achievement of five yen tag inlet during August, 2006 [A. Honzawa, et al.,2007]. In addition, tag that improved security was developed after August 2006. Besides gHibikih project, RFID tag equipped with a high-speed, mass memory that sounded and used FeRAM (Ferroelectric Random Access Memory) appeared [H. Nakamoto, et al.,2007].

The antenna that miniaturized tag was researched and developed so that it was installed in the center part of CD or DVD [A. S. Andrenko, et al.,2007]. On the chip antenna was researched and developed as an attempt that tag size reducing more [H. Abe, et al.,2005], [M. Usami, 2006].


As the RFID system, it researched concerning interference [Y. Tanaka, et al.,2007] and the readout performance improvement technology of the simultaneously multiple tag data access method, etc [J. Mitsugi, et al.,2007], [T. Maniwa,et al.,2007].


UHF band RFID is applied to the stock management of the household appliance store, the production control of the personal computer, the application of the Toyota just-in-time system to the production system, the lending management of crates, and the management of the uniform, etc. as a present business system.


It is scheduled for UHF band use for not only a passive type but also active type RFID to be examined in 2007, and to become possible to use in 2008.

(T. Maniwa)




J. Mitsugi and H. Hada[2006],hExperimental study on UHF passive RFID readability degradationh, International Symposium on Applications and the Internet Workshops 2006 (SAINT Workshops 2006).


Y. Kawakita and J. Mitsugi[2006], gAnti-collision performance of Gen2 air protocol in random error communication linkh, International Symposium on Applications and the Internet Workshops 2006 (SAINT Workshops 2006).


A. Honzawa, Y. Kobayashi, S. Fukushima and T. Yamazoe[2007],h The achievement of Hibiki Project - for the spread use of RFID –g, International Symposium on Applications and the Internet Workshops 2007 (SAINT Workshops 2007).


H. Nakamoto, D. Yamazaki, T. Yamamoto, H. Kurata, S. Yamada, K. Mukaida, T.  Ninomiya, T. Ohkawa, S. Masui and K. Gotoh[2007],h A Passive UHF RF Identification CMOS Tag IC Using Ferroelectric RAM in 0.35-um Technologyh, IEEE Journal of Solid-State Circuits, Vol.42, No.1, pp.101-110.


A. S. Andrenko, M. Kai, T. Maniwa and T. Yamagajo[2007], hCompact printed-on-CD UHF RFID tag antennash, 2007 IEEE Antennas and Propagation International Symposium, pp. 5455 – 5458.


H. Abe, M. Sato, K. Itoi, S. Kawai, T. Tanaka, T. Hayashi, Y. Saitoh and T. Ito[2005], h Microwave operation of on-chip antenna embedded in WL-CSPh, 2005 IEEE International Workshop on Antenna Technology: Small Antennas and Novel Metamaterials( IWAT 2005), pp.147-150.


M. Usami[2006], gUltra-Small RLID Chip Technologyh, 13th IEEE International Conference on Circuits and Systems (ICECS '06), pp.708-711.


Y. Tanaka and I. Sasase,[2007]h Interference Avoidance Algorithms for Passive RFID Systems Using Contention-Based Transmit Abortionh, IEICE TRANSACTIONS on Communications Vol.E90-B, No.11, pp.3170-3180.


J. Mitsugi and Y. Shibao[2007],h Multipath Identification using Steepest Gradient Method for Dynamic Inventory in UHF RFIDh, International Symposium on Applications and the Internet Workshops 2007 (SAINT Workshops 2007).


T. Maniwa, H. Sugano and M. Kato[2007], hMass Data Read/Write Technology for UHF-Band RFID Tagsh, Fujitsu Scientific & Technical Journal(FSTJ), Vol.43, No.4, pp.464-468.



C9. Ubiquitous Power Source


Ubiquitous Power Source (UPS) was proposed in Japan [Shinohara et al, 2005] and research and development activity has been higher in Japan for these three years.


Weak point of future ubiquitous information society is power source. We can get information in every time and in everywhere in the ubiquitous information society. However, all information equipments like note PC, mobile phone, and PDA, need battery and the other power source. The power source restraints the time and the place of the ubiquitous information society. So the UPS supplies wireless power via microwave. We use only carrier of the non-modulated/modulated microwave to transmit the wireless power. Passive RF-ID is close to the UPS.


Key technology is rectenna, rectifying antenna, which rectify the microwave to DC with high efficiency. The RF-ID has the rectenna in the chip. Some developments of the rectenna for the RF-ID or the UPS have been done in Japan [Shinohara et al., 2004] [Takagaki et al, 2006] [Kitayoshi et al, 2006]. They use Shottokey Barrier Diodes for the rectifier of the rectenna. The SBD is not special and only for the communication system.


In Japan, research and development activity of the wireless power transmission (WPT) for the Space Solar Power Satellite/Station (SPS) has been high for over twenty years [Matsumoto, 2002][Fujita et al., 2007] [Mihara et al., 2007]. The UPS is based on the WPT technologies.

(N. Shinohara)




Shinohara, N., T. Mitani, and H. Matsumoto [2005], gStudy on Ubiquitous Power Source with Microwave Power Transmissionh, Proc. of International Union of Radio Science (URSI) General Assembly 2005, C07.5(01145).pdf


Shinohara, N., H. Matsumoto, A. Yamamoto, H. Okegawa, T. Mizuno, H. Uematsu, H. Ikematsu, and I. Mikami [2004], gDevelopment of High Efficiency Rectenna at mW Input (in Japanese)h, Proc. of 7th SPS Symposium, pp.105-110


Takagaki, T., K. Fujimori, M. Sanagi, and S. Nogi [2006], gImprovement in Conversion Efficiency of a Rectenna Circuit by considering Harmonics (in Japanese)h, Proc. of IEICE 2006, CBS-1-3.pdf


Kitayoshi, H. and K. Sawaya [2006], gA Study on Rectenna for Passive RFID-Tag (in Japanese)h, Proc. of IEICE 2006, CBS-1-5.pdf


Matsumoto, H.[2002], gResearch on solar power satellites and microwave power transmission in Japan,h IEEE Microwave Magazine, vol.3, no. 4, pp. 36-45


Fujita, T., H. Suzuki, M. Mori, and Yuka Saito [2007], gSummary of Studies on Space Solar Power Systems of  Japan Aerospace Exploration Agency  (JAXA)h, Proc. of International Symposium on Radio Systems and Space Plasma (ISRSSP), pp.137-140


Mihara, S., T. Saito, Y. Kobayashi, and H. Kanai [2007], gActivities for the Realization of Space Solar Power System at USEFh, Proc. of International Symposium on Radio Systems and Space Plasma (ISRSSP), pp.149-152



Shozo Komaki

Osaka University



Kenji Itoh

Mitsubishi Electric


Tadashi Kawai

University of Hyogo


Katsutoshi Tsukamoto

Osaka University


Hirotsugu Kubo

Mitsubishi Electric


Minoru Okada

Nara Institute of Science and Technology


Mitoshi Fujimoto

University of Fukui


Akihito Kato

National Institute of Information and Communications Technology


Toru Maniwa

Fujitsu Laboratories


Naoki Shinohara

Kyoto University